Questions tagged [rf]
Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.
2,522
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Compensation for dielectric losses in a coil?
Recently I built a helical resonator. It took me a good while to adjust it since I had to trim my coils much shorter than calculated. The calculation said 7.2 turns but it ended up being more like 6.5 ...
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2answers
71 views
Avoiding ground loops with multiple coax cables
I have to connect two devices with multiple coax cables each carring a signal that has frequency components ranging from DC to a few GHz. I don't know how to avoid ground loops with this type of ...
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1answer
56 views
How much RF power can a microstrip line handle?
Transmission lines on printed circuit boards must be impedance controlled lines since we want to transmit the full power and avoid the reflections.
Microstrip lines have three parameters that we can ...
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3answers
81 views
Why is a horizontal rod a full wavelength oriented radially to a broadcast antenna not the best receiving antenna
I have always struggled to get a good physical understanding of Electromagnetic waves. I've done the whole Maxwell's equation approach, wrote boundary element solver tool but cannot rationalize that ...
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1answer
53 views
What is the purpose of these components in an LC Balun?
I'm trying to understand an antenna impedance matching / balun network that I came across in the receiving signal path in the schematics for the STEVAL-FKI868V2 S2-LP Evaluation Board, shown in the ...
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14 views
Butler Matrix simulation in Sonnet software
I am trying to replicate a 4 X 4 butler matrix using Sonnet
Here is the sonnet design file : butler_matrix.son
With conformal meshing (metal fill type) and course meshing, it still requires 14 GB of ...
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1answer
37 views
GPS module accuracy query
I have a GPS module with an accuracy of 1.5m + 1 ppm.
Query: What is meant by 1 ppm accuracy, what does it symbolize?
3
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1answer
52 views
How do I create a 50ohm input impedance into this RF power measurement IC
I'm trying to create a basic RF power meter using the LTC5532.
I want to add a SMA connector, and termination, so that the device has a 50ohm input impedance. I'll be using it primarily at 2.4Ghz, ...
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27 views
Relation between Centre Frequency and PLL locking range in FM Demodulation?
I am implementing an all digital PLL FM demodulating system using an FPGA. My center frequency is that of 125kHz and for some reason, the PLL is only locking at +/-38khZ from the center frequency, ...
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1answer
55 views
How the diode in this circuit achieves AM modulation
For the last week, I've been looking for a simple circuit to transmit VHF
analogue TV video signals, so that I can transmit my Raspberry Pi output to a TV set. Since I don't have enough experience in ...
3
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1answer
847 views
Avoiding microstrip line to become CPWG
I have been designing RF PCBs for a year for an RF front-end system.
One of my PCBs has very strict constraints about its size measurements.
So, I should design it very densely.
The problem with ...
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48 views
Request for a RF technolgy [closed]
Request you to suggest a RF module which can communicate over a distance of 3km as shown in the below figure
Application: used in farming field
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1answer
28 views
Stream Audio and WebCam Video through Radio Frequency
I and my friend would love to make a better communication system between us since his internet connection is not the best and neither is mine. We are 20 km away from each other.
Our project is to ...
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28 views
Transmitting VLF RF signal using a LW transmitter [duplicate]
In reference to a previous thread I have created a visual basic 6 program that can output an audio sine wave out of the 3.5 aux speaker jack on the PC soundcard.
The sine wave is broadcasted as either ...
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0answers
11 views
Is HID 125 kHz mini mullion proximity reader Compatible with Suprema DM-20 and Corestation?
Can we use HID Proximity cards and HID 125 kHz mini mullion proximity reader for suprema DM-20
and Corestation Controller using wiegand connection? If they are compatible how many DM-20s
would be ...
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2answers
53 views
Can someone please explain this Bluetooth Antenna Test Result, I am new to RF?
This is the test of a Bluetooth (BLE 5.0) passive antenna test result. I am new to RF and do not know how to properly interpret this result.
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52 views
Video transmission wirelessly [closed]
I need to transmit a video file wirelessly. Its size will be 3Mb maximum. Resolution depends on the video and i can change the fps value as i wish.
The video file will be given in a SD card or a ...
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1answer
30 views
BLE beacons advertising frequencies collision
I'm designing a smartphone app that gets advertising transmissions from N BLE beacons that transmit to M meters (approximately), for kind-of indoor-navigation. My goal is to maximize N and M as ...
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36 views
TCXO with tune-able Frequency
Hello I need a TCXO with tunable frequency 10 to 12MHz. I find the part here A18ST but this company is not responding and I don't find their distributors. Please help me if anyone knows a company that ...
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1answer
55 views
What causes 100Hz spuriour emissions on AD9850 WSPR transmitter?
I've built WSPR transmitter based on AD9850.
AD9850 is driven by 125 MHz crystal. TX frequency is 14 Mhz.
On the receive side there is upconverter (+125 MHZ crystal) and SDR (both RTL-SDR and AirSpy). ...
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2answers
76 views
How to drive an AD9850 at 100 kHz/s sweep using arduino or rasberry pi?
The basic problem I am interested in doing is using an ADXXX chip to make a linear frequency sweep through the HF bands, from 1-20 MHz. The sweep rate I would like to achieve is 100 kHz/s, which ...
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0answers
29 views
Si4362 Reciever operating outside band
Fellow engineers, I have RF related problem
I've found interesting receiver chip which I intend to use outside designated band.
Si4362
It is stated in datasheet that:
Frequency range = 142–1050 ...
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0answers
20 views
Radio frequency coil for homogeneous B field over area
Are there any possibilities of creating a coil which would function at high frequency (MHz range , maybe up to a few GHz) and which would give me a B field that could be used to penetrate a certain ...
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1answer
46 views
Is there a RF signal device for a 120 or 240 vac wire to start and stop a standby generator?
Our standby generators automatically start when a switch in the automatic transfer switch closes and the gen stops when that switch opens. Usually we bury 2 16ga wires along with two 120/240v hot and ...
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23 views
Whats the difference in these 2 input filter dampers?
Hi Im designing input filter for tps54202, with input 12V, output 3.3V at 0.5A. To pass emission test I need input filter, L+C should be good for that, but Ive read that its good to add damper to get ...
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1answer
31 views
RF shield needed for BLE SoC in PCB design
I´m checking the implications of using BLE in a new design.
This design will include in the same PCB a BLE SoC, the specific matching network and an anetnna (still checking if I´m going to use a ...
3
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1answer
133 views
How to deal with ground in VCCed-chassis device?
I'm restoring old USSR radio receiver ("Okean-209"). I've already resoldered all electrolytic capacitors so audio amplifier works great again (there was very low sound before that). However, there are ...
2
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2answers
59 views
Extending an RF ground plane outside a small PCB
I am making an RF PCB with a surface-mount antenna on it. It is a quarter-wave antenna, so the ground plane should also be as long as a quarter wavelength for good RF performance.
For example, a ...
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1answer
52 views
Measurement of s11 with reduced power on NanoVNA
I am developing a 10.7 MHz IF amplifier for a radio receiver. In order to match the input to the output of the driving mixer stage (330 ohm) I need to measure the input impedance.
I did the ...
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1answer
33 views
Task of the Driver on Mach Zehnder Modulator
What is the task of the Driver of the MZM modulator? I'm trying to get RF input for the MZM, does the driver convert optical input to RF?
We have a driver, what's the purpose of it? How can I design ...
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1answer
43 views
Doubts about a differential negative resistance oscillator
let's consider this kind of differential negative resistance oscillator:
The output of this circuit is VA - VB. My book says the following sentence:
From a quick analysis of the circuit it can be ...
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29 views
How can I setting up RF2506?
I'm going to use RF2506 IC in my project.
But I want to know How can I calculate the output frequency.
I searched the Internet but I find nothing.
I want to change only VTUNE voltage to control the ...
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0answers
67 views
How to add a 4g / 5g feature on a single board computer design with a cheap price?
Let's assume, I am planning do design my own single board computer just as a hobby regardless of whether it is wise or not.
Searching online has made me so confused.
In general, I see two options:
...
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1answer
39 views
Impedance matching an amplifier near 1 dB compression point
I am using a RF amplifier (model: Minicircuits LZY-22+) to drive 6.5 MHz oscillation in a coil. I am using an antenna tuner (model: MFJ-969) to impedance-match the output of the amplifier to the coil. ...
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3answers
69 views
In Amplitude Modulation transmission, why do we need to mix (multiply) rather than just add the carrier and base-band?
Why is it necessary to mix the carrier with the message signal to create the sum and difference of the frequencies when you can just add both signal?
Not only is it much easier to achieve but it would ...
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1answer
47 views
How this remote control generates radio signal?
I have this RF remote control that I'm trying to understand (here is spec: http://www.telran.co.il/images/980305%20QK-M04%20TECH%20SPECS.pdf ).
I recognize crystal oscillator that is responsible for ...
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2answers
43 views
4G LTE: Is it possible to make a high gain antenna that resonates well for two frequencies, where one isn't a close harmonic of the other?
I want a high gain antenna for Verizon LTE data to my JetPack 7730L but don't really see one as high as say this MIMO parabolic antenna that's probably design for 2.4 GHz WiFi. From all I know it's ...
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38 views
Zero - IF receiver main limits
I was reading these slides about receivers architectures, and I have some questions about Zero - IF receivers:
Precisely:
Why is the spectrum around the carrier (i.e. the 2 "side bands") mirrored ...
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36 views
Building a Bluetooth dongle from scratch
I am trying to build a custom wireless mouse and I was initially a bit confused on how "wireless" can be implemented. What I was confused about is how some mice have dongles while others simply pair ...
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0answers
48 views
RF signal Multiplier or Chopper
I'm trying to design a circuit that "multiplies" two signals.
I have an electrical unit with two separate circuits. One circuit drives the other one with a square signal. The width of the square ...
0
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1answer
36 views
Good solution for TPS54202 input filter design?
I trying to make tps54202 switch regulator for esp32-wroom which would pass EMC test.
https://www.ti.com/tool/TIDA-00948
By reading guidelines of designing they say that to pass EMC test you need to ...
0
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3answers
94 views
Can I use a 2.4 GHz rated parabolic MIMO antenna for 700 MHz Verizon 4G LTE data?
Can I use a 2.4 GHz rated parabolic MIMO antenna for 700 MHz Verizon 4G LTE data?
It seems 700 MHz are a long ways from the range of a 2.4 GHz antenna, but I have seen people marketing similar ...
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2answers
29 views
Antenna Tuning for a Multi-band Antenna
I have PCB antenna . which support multiple band antenna.
https://www.johansontechnology.com/datasheets/0830AT54A2200/0830AT54A2200.pdf
we also have tune circuit before antenna as recommended by ...
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1answer
26 views
Can capacitors be used to make a low-impedance ECL termination voltage?
I am trying to develop a circuit in which an RF sinusoid is put into the input of the ADCMP552 PECL output comparator and then the PECL output (square wave ish) is input to the MC100EP140 phase ...
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2answers
54 views
Is the TPS54202 buck converter a good solution to pass the FCC SDoC?
I want to design a PCB with the ESP32-WROOM module which has bluetooth. I want to pass the FCC verification. I would use a linear regulator, but it makes too much heat. My input is 14V car battery, ...
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1answer
42 views
Value of loop gain for steady state oscillations
I was reading on a book (High-Frequency Oscillator Design for Integrated Transceivers, J. van der Tang, Dieter Kasperkovitz, Arthur H.M. van Roermund) this paragraph about the start-up condition for ...
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0answers
94 views
Why are tv aerial cables so mysteriously sensitive to their positioning and the proximity of people?
Digital TV Reception is not great in our area and sometimes we lose reception when conditions aren't favourable. Being UK Freeview, I'm pretty sure it uses the DVB-T2 standard.
Anyway, when ...
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2answers
60 views
How is the closed loop transfer function defined for an oscillator?
an electronic oscillator is a device which can generate some signals without input signals. It is an unstable system realized with positive feedback, as shown in the following scheme:
Now I have two ...
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2answers
65 views
Relationship between radio transmitter output power and its input electrical power?
Given a radio station of a given licensed effective radiated power, is it the case that the transmitter requires at least that much mains power to run it? E.g., if a radio station says it's 100,000 ...
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1answer
75 views
Direction finder for cross country navigation while dayhiking - antenna considerations [closed]
Edit: I'm looking for an antenna, not criticism on whether I need one, all the rest is just background😉
My family enjoys short day hikes through heavily wooded countryside with mild hills.(Northen ...
